Table 1.

Amino acid analysis of three purified bovine nuchal ligament elastin samples (samples 1–3, described in the text), unpurified elastin and their relative desmosine concentration. The amino acid measurements are reported as “residues per 1000 residues (res/1000)” for ease of comparison with other published results³⁷. The theoretical values, shown in column 6, correspond to the amino acids computed from cDNA of bovine tropoelastin⁴³. The relative desmosine concentration represents the ratio of desmosine to d₄-desmosine, normalized by the unpurified sample (starting product). Note that the concentration of lysine in the theoretical value (column 6) is higher than that in samples 1–3 and the unpurified sample, as cross-links consist of lysine.

	res/1000
	Sample 1	Sample 2	Sample 3	Unpurified	Theory*
Asx	5.6	4.6	4.1	4.2	4
Thr	6.9	5.5	6.8	1.0	11
Ser	7.1	6.4	7.3	0.0	10
Glx	14.5	14.9	14.0	19.7	14
Pro	147.5	149.2	153.2	121.0	119
Gly	335.9	332.6	329.7	325.3	319
Ala	238.3	237.6	238.4	229.1	211
Val	121.8	125.3	123.7	125.5	126
Cys	-	-	-	-	-
Met	0.0	0.0	0.0	0.0	-
IIe	21.9	22.2	22.2	21.1	25
Leu	53.7	54.6	53.9	62.7	60
Tyr	6.9	7.3	7.2	17.4	10
Phe	33.2	34.3	34.6	38.4	29
His	0.0	0.0	0.0	10.4	0
Lys	2.4	1.9	1.9	10.9	53
Arg	4.3	3.6	3.0	13.3	7
Relative desmosine concentration	1.00±0.10	1.09±0.12	0.86±0.10	1.00±0.14	-